Rearview periscope adjustment means for vehicles

ABSTRACT

A rearview periscope system for vehicles including three mirrors, at least one of which is mounted within the vehicle. This mirror located within the vehicle has a novel mirror supporting and adjustment means which allows the adjustment of both the distance of said mirror from the other mirrors along the central sightline of the reflected mirrors, and the angular position of the plane of said mirror with respect to the planes of the other mirrors.

United States Patent 1191 [11] 3,774,996 Donnelly 1 Nov. 27, 1973REARVIEW PERISCOPE ADJUSTMENT 3,589,663 6/1971 Vance 248/480 3,488,0261/1970 Wallace et al. 248/480 MEANS FOR VEHICLES H n d M h 3,367,6162/1968 Bauschet et a1. 248/483 [75] Inventor John Donne 0 an FOREIGNPATENTS OR APPLICATIONS [73] Assignee: Donnelly Mirrors, Inc.. Holland.924,721 0/1963 Great Britain 350/302 Mich.

Filed: Aug. 22, 1972 Appl. No.: 282,705

Related US. Application Data Continuation of Ser. No. 167,730, July 30,1971, abandoned.

US. Cl 350/302, 248/480, 350/307, 350/299 Int. Cl. G02b 5/08 Field ofSearch 350/288, 299, 301, 350/302, 307; 248/480, 481, 295, 298

References Cited UNITED STATES PATENTS Smith Stone Mattsson 350/302Primary ExaminerDavid Schonberg Assistant Examiner-Michael J. TokarAttorney-Peter P. Price et a1.

[ 5 7] ABSTRACT A rearview periscope system for vehicles including threemirrors, at least one of which is mounted within the vehicle. Thismirror located within the vehicle has a novel mirror supporting andadjustment means which allows the adjustment of both the distance ofsaid mirror from the other mirrors along the central sightline of thereflected mirrors, and the angular position of the plane of said mirrorwith respect to the planes of the other mirrors.

19 Claims, 10 Drawing; Figures PATENTEDHOV 21 ms SHEET 3 BF 3 aCEMT'RAL.

SIGHTLI ME 31 @pF LN m w m w m REARVIEWPERISCOPE ADJUSTMENT MEANS FORVEHICLES This application is a continuation of pending application Ser.No. 167,730, filed on July 30, 1971, now

abandoned.

This invention relates to periscope systems for vehiclesand, moreparticularly, to rearview periscope systems incorporating adjustmentmeans for at least one mirror disposed. on the interior of the vehicle.

BACKGROUND OF THE INVENTION Rearview periscope systems for vehicles arewellknown in the art. Such systems, utilizing at least three mirrors incombination, have been designed to increase the field of vision of thedriver of a vehicle incorporating such a system, thereby making drivingan easier and safer task. Typically, the prior systems utilized threemirrors arranged within the confines of a box which in turn wasprojected through the roof of the vehicle in order to reflect the lightrays from the exterior of the vehicle to the interior. Although thesearrangements did, in fact, increase the field of vision, they were allcharacterized by a common defect, that being the inflexibility of thosesystems. Typically, the viewing mirrors were positioned. in a fixedposition, near the roof of the vehicle. Thus, when the driver desired touse the mirror to view the traffic situation behind the vehicle, he didnot get a full rear view unless he tilted his head or shifted his eyesso as to disturb his normal driving position which frequently resultedin taking his eyes completely off i the roadway.

Similarly, the inflexibility of the prior systems produced otherdisadvantages. The most notable of these was the inability of thesesystems to accommodate drivers of different sizes whose eyes are locatedat different levels and distances from the mirrors. Thus, when a shorterperson desired to use the fixed mirrorsystems, he had to pull himself upin theseat, thereby losing all concentration on his driving, or use someother means of support to raise his eye position. Similarly, a driverwith long legs or short legs had to adjust himself to obtain full visionfrom the mirror system. Some of the later systems incorporated means bywhich the first mirror could be tilted in order to accommodate differentsize persons. However, even when the mirror was tilted, a person havingan eye position located a greater distance than normal from the firstmirror lost a sub stantial part of the field of vision possible with themirror system, since the remaining mirrors in the system could not beadjusted. Further, a driver having an eye position located a shorterdistance than normal from the first mirror would see the boundaries ofthe other unadjustable mirrors which was very disturbing to the driver.Consequently, the utility of these prior systems was severely reducedsince they could accommodate only persons of a common size.

Accordingly, the need was readily apparent for a rearview periscopesystem which was convenient to use and which was flexible enough toaccommodate nearly all the various sized adult persons who would bedriving the vehicles incorporating the system. Responsive to this need,the primary objective of this present invention is to provide a rearviewperiscope system adjustment means which allows the accommodation ofnearly every size of adult person who will conceivably utilize thevehicle incorporating the periscope system. Similarly, it is anotherobject of the present invention to provide a rearview periscope systemadjustment means which places the first or viewing mirror, into whichthe driver of the vehicle looks, in a position which is both veryconvenient and safe to use. It is yet another object of the presentinvention to provide a rearview periscope system adjustment means whichis simple and easy to operate.

SUMMARY OF THE INVENTION The novel and inventive features of the presentinvention may beaccomplished by providing a rearview periscopeadjustment means described as follows. The novel adjustment means isincorporated in a rearview periscope system comprising three mirrors, atleast one (the first) of which is mounted within the interior of thevehicle. At least one mirror (the third) reflects the light rays fromthe rear of the vehicle through a cover glass into the interior of thevehicle by way of reflecting the same from a second mirror locatedbetween the first and third mirrors. In accordance with this invention,the first mirror is mounted with relation to the other two mirrors so asto provide a novel adjustability with relation thereto, the combinationthereof providing the desired feature of accommodating all sizes ofdrivers while keeping the rearward field of vision nearly exactly thesame for each driver. This is accomplished by using an adjustment meanswhich is movable along the central sightline of the mirror systemwithout the necessity of changing the angular position of the plane ofthe first mirror with respect to the second mirror, and also providing ameans for angularly adjusting the first mirror with respect to theothers. The adjustment means maintains the total optical path lengthfrom the drivers eyes to the third or exterior mirror within a specifieddistance range by moving only the first or viewing mirror along thesightline toward the second mirror. At the same time, the viewing mirrorremains at a substantially constant angle above the horizontal planesincluding the eyes of vario'ussized drivers. As a result, the field ofvision for each sized dn'ver remains substantially the same.

In the preferred embodiment, this adjustment is accomplished byproviding a first mirror supporting means mounted at or near the top ofthe windshield. The supporting means comprises a support member having areceptacle formed therein to receive a corresponding sliding member withthreaded means to secure the slide in the receptacle of the supportmember. On the end of the slide nearest the second mirror, is positioneda ball joint on which the first mirror is pivotally mounted. Therefore,to accommodate a driver whose eye position is lower and closer to thewindshield, the securing means may be loosened permitting the slide, tobe slid toward the dashboard of the vehicle in a direction away from theeyes of the driver. The axis of travel of the slide, as mentionedbefore, is parallel to the central sightline of the mirror system. Thus,in this example, although the first mirror is lowered sufficiently toallow the smaller person to conveniently view its surface, it hasremained in exactly the same position with respect to the centralsightline, and the angular position of the plane of its mirror surfacehas not changed with respect to the angular position of the plane of thesecond mirror surface. Further, as explained above, the total opticalpath length of the system, as well as the angular position of the firstmirror above the horizontal plane including the drivers eyes, remainsubstantially the same for generally all sizes of drivers. Therefore,the field of vision as viewed in the first mirror remains substantiallythe same for all sized persons. The swivel ball joint is provided on theend of the slide in order to provide means for making minor correctionsin the field of vision, i.e., to minimize the viewing of the frame'ofthe second and third mirrors, etc.

These and other objects, advantages and features of the invention willbecome apparent from a study of the following description taken inconjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of theexterior of the roof section of a vehicle incorporating the rearviewperiscope system;

FIG. 2 is a cross-sectional view of the complete periscope system takenalong line IIII of FIG. 1;

FIG. 3 is an elevational side view of the preferred embodiment of thesupporting and adjustment means utilized in the present invention;

FIG. 4 is a fragmentary cross-sectional view of the preferred embodimentof the supporting and adjustment means taken along line IVIV of FIG. 3;

FIG. 5 is an elevational side view of an alternative embodiment of thesupporting and adjustment means;

FIG. 6 is a fragmentary bottom view of an alternative embodiment of thesupporting and adjusting means takenalong line VIVI of FIG. 5;

FIG. 7 is an elevational side view of yet another alternative embodimentof the supporting and adjusting means;

FIG. 8 is a schematic drawing of the range of adjustments allowed by theembodiments of the present invention;

FIG. 9 is a schematic top view of the periscope system showing theadjustment means shifted from the central sightline to rotate therearward field of vision; and

FIG. 10 is a schematic view of the mirror system aligned in a linearorientation for explanation purposes showing the boundaries of thefields of visions as the first mirror is moved along the centralsightline between an eye position and the second mirror.

DESCRIPTION OF THE PREFERRED EMBODIMENT In reference to the drawingsgenerally, a rearview periscope system is shown generally at 10. Theperiscope system comprises a third or extra-vehicular mirror 12 fixedlymounted within an aerodynamically designed cowling 14 in the shape of apartial air foil. The cowling 14 is supported by struts 16 and ismounted on the roof of the vehicle 11, generally over the area in whichthe driver would sit. The third mirror 12 faces rearward and collectslight rays from the rear of the vehicle which are traveling generallyparallel to the roof of the vehicle and the ground over which ittravels. The collected light rays are reflected generally verticallydownwardly by the third mirror 12 through a transparent cover means 18which is supported over an opening formed in the roof of the vehicle bya cover plate 20. The reflected rays strike a second mirror 22 which ismounted in a breakaway fashion (further described herein) on supportbrackets 24. The second mirror 22 in turn reflects the light raysdownwardly at an angle to a first mirror 26. The first mirror 26 in turnreflects the light rays to the eye of the driver of the vehicle (notshown). The reflected light rays are slightly nonparallel and are seento be reflected in a generally converging manner through the threemirror system towards the eye of the driver. The central sightline 28thus follows the path of the central-most reflected light beam throughthe mirror system 10.

In accordance with this invention, I have provided in the abovecombination the concept of adjusting the first mirror 26 along thecentral sightline 28 of the system while maintaining the remaining twomirrors a constant distance from one another. Also,'independently ofsuch sightline adjustment, the first mirror can be adjusted angularlywith respect to the other mirrors. This novel adjustment is accomplishedby means of the supporting and adjustment means for the first mirror 26shown generally at 30. The adjustment means 30 comprises a supportmember or base 32 mounted on a support stamping 34 which is in turnfixedly attached to the roof 11 in the vicinity of the interior of thetop of the windshield (not shown). Received in a receptacle 36 in thebase 32 is a slide 38 supporting a ball joint 40 on the end of the slide38 nearest the second mirror 22 on which is swivelly mounted firstmirror 26. Securing means (not shown in FIG. 2) are incorporated withbase 32 and slide 38 to secure slide 38 at various positions. Thereceptacle 36 is formed within base 32 so as to have its longitudinalaxis parallel to the central sightline 28a (between the first and secondmirrors) of the mirror system. Thus it is apparent that the slide 38,and thus first mirror 26, may be slid toward and away from base 32 alongsightline 28a, thereby keeping the first mirror 26 in exact alignmentwith the central sightline 28a of the entire periscope system withoutthe actual physical adjustment of the first mirror 26 itself.Consequently, regardless of the position of the slide 38, the firstmirror 36 will be in exact relative alignment with the second and thirdmirrors 22 and 12, respectively, thereby insuring that, upon properadjustment, the field of vision of the driver, no matter what hisphysical size, will be substantially the same. Since the range of travelof the slide 38 approximately includes only 5 or 6 inches, it isapparent that the first mirror 26 will always be near the top of thewindshield on the interior of the vehicle thereby insuring that thefirst mirror 26 will be conveniently located for all sizes of drivers.Therefore, in vehicles in which the driver sits on the left-hand side ofthe vehicle, the system is designed to allow the adjustment of the firstmirror to be located at an angle within the range of between about 3037above the horizontal position of the drivers eyes, as shown in FIG. 8,in the area above the upper right-hand quadrant of the steering wheel,thereby allowing the driver to view the rearward field of vision withonly a slight movement of his eyes. Thus, he need not remove his eyesfrom the path of the vehicle for any extended period of time, therebyinsuring his control of the vehicle and his ultimate safety at alltimes. The adjustment means provides substantially the same angularrelationship of first mirror to horizontal plane including the driverseyes for generally all sizes of drivers. As noted above, this isgenerally 30-37 for all drivers.

To further facilitate the convenient adjustment of the first mirror 26,the adjustment means may include a plurality of check stops, or built-inadjustment positions, which will automatically be engaged as the slide38 is moved towards or away from the second mirror 22. Thus, thesecuring means (not shown in FIG. 2) would automatically engage thesecheck stops without the driver having to consciously tighten or engagethe securing means at these positions.

Referring now more particularly to the exact embodiments of theadjustment means, the preferred embodiment is shown at 50in FIG. 3. Suchadjustment means comprises a support member or base 52 having agenerally rectangular cross section as shown in FIG. 4. Formed centrallytherein is a slot 53 having a T-shaped cross section corresponding to aT-shaped slide 56 slidably mounted therein. End caps 54 are mounted onthe ends of the base 52 to prevent the slide 56 from sliding completelyout of the T-shaped slot 53. Slide 56 has a surface 57 formed integrallytherewith at an angle of approximately 40 to 45 with the longitudinalaxis 55 of the slide 56. Lesser angles may also be used depending on theparticular orientation desired for mirror 26. A ball joint 58 is mountedperpendicularly with surface 57. Ball joint 58 receives one end of adouble ball joint receptacle or swivel spacing member 59 such that theopposite end of the receptacle 59 is left open to receive a second balljoint 60 mounted on the back of first mirror 26 such that the positionof the first mirror 26 may be changed by swiveling either ball joint 58or 60. Slide 56 also includes a threaded hole 62 which receives setscrew with an enlarged head 64 such that by tightening or loosening theset screw, the slide 56 may be secured or loosened to allow movementfrom position to position.

The operation of the adjustment means 50 incorporated within periscopesystem will now be apparent. The support member or base 52 is mountedwith its longitudinal axis 55 parallel to the central sightline 28arunning between the first and second mirrors on support stamping 34located in the vicinity of the top of the windshield in the area of theupper right quadrant of the vehicle steering wheel (not shown). Toaccomplish the first mirror adjustment, the vehicle driver positionshimself in the drivers seat and glances slightly upward to sight thesurface of the first mirror 26. In order to obtain optimum field ofvision without viewing the bound aries of the mirrors, his line of sightis bounded generally by the light rays C and D, as shown in FIGS. 3 and10. As shown in FIG. 10, where the mirror system is shown with thevarious mirrors arranged linearly along the central sightline tofacilitate an understanding of the changes in the boundaries of thefield of vision as the first mirror is adjusted in accordance with thisinvention, if the first mirror 26 is positioned too close to the driverseyes, as represented by position I, the driver in viewing the mirror hasa line of sight bounded generally by light rays C and D As a result, thedriver will see the boundaries of the second and third mirrors when thefirst mirror is in position I. On the other hand, if the mirror ispositioned at position II, the driver has a line of sight boundedgenerally by light rays C and D and as a result will have too a limitedfield of view. Thus, the full capacities of the second and thirdmirrors, 22 and 12 respectively, will not be utilized in position ll.However, when properly positioned at position 111, the line of sightwill be bounded by the light rays C and D to give optimum field of viewwithout annoyance of seeing the boundaries of both the second and thirdmirrors. It should be understood that mirror sizes for the presentsystem are chosen to accommodate both tall and short persons. Mirrorsizes must be larger to accommodate taller persons. Accordingly when thesystem is adjusted for shorter persons, the field of view remainssubstantially the same although the image of that field does notnecessarily fill the entire first or viewing mirror. Thus, shorterpersons may see a portion of the boundary of the second mirror. However,no more than this one mirror boundary will be seen by any person usingthe system since the second and third mirrors are I kept a constantdistance apart resulting in their full surfaces and capacities beingutilized for all adjustments of the system.

Minor angular adjustments can be made by means of ball joints 58 and 60.This simple, one-handed adjustment is made possible since thelongitudinal axis 55 of thebase member 52, slot 53, and thus slide 56,are parallel to the central sightline 28a of the light rays beingreflected between the first and second mirrors 26 and 22, respectively.Therefore, wherever slide 56 is positioned within slot 53, the firstmirror 26 will be in exact alignment with the central sightline 28a,thereby obviating any major adjustments other than the movement of slide56 to accommodate shorter or taller persons.

DESCRIPTION OF THE ALTERNATIVE EMBODIMENT FOR THE ADJUSTMENT MEANSReferring to FIGS. 5 and 6, an alternative embodiment of the adjustmentmeans is shown generally at 70. Mirror support means comprises agenerally cylindrical swivel support member 72 having a cylindrical hole74 bored therethrough along longitudinal axis 73. Formed integrally withsupport member 72 is a generally cylindrical extension 76 having acylindrical hole 78 bored therethrough along axis 80. Axis 80 isperpendicular to axis 73. The swivel support member 72 is swivellymounted on support stamping 34 by means of a ball joint 82. A set screw84 is threadably received in threaded hole 78 and may be tightenedagainst ball joint 82 to adjust the amount of friction on the ball joint82. A slidable rod 86 is received in. cylindrical hole 74 and has a slot87 (see FIG. 6) formed along the surface thereof. The rod 86 is securedin hole 74 by means of a set screw 88 threadably received in a threadedhole 89 bored perpendicularly to the axis 73 of hole 74 such that setscrew 88 may be advanced into slot 87 to secure rod 86 in variouspositions. Mounted at the end of rod 86 closest to the second mirror 22,is a second ball joint 90 mounted to be substantially horizontal. Balljoint 90 is received in a receptacle 91 mounted on the back of firstmirror 26 such that first mirror 26 may be swiveled for minoradjustments.

The method of adjusting means 70 to accommodate various sized driverswill now be apparent. First, the axis 73 of the hole 74, and thus rod86, must be positioned to be parallel to the central sightline 28abetween the first and second mirrors. This is accomplished by looseningset screw 84 positioning the rod 86 and swivel mounting 72 such that theaxis 73 is parallel to the sightline 28a, and then tightening set screw84 to retain the rod 86 and base 72 in the parallel position. Once thisparallel adjustment has been made, set screw 84 need not be furtheradjusted unless it becomes loosened and allows the base 72 to swivel outof the parallel position. Major adjustments to accommodate various sizeddrivers may be made by loosening set screw 88 and allowing rod 86 toslide from position to position as shown in the phantom lines in FIG. 5.Thus, it is apparent that the periscope system may be adjusted toaccommodate all sizes of vehicle drivers by incorporating the noveladjustment means 70.

FIG. 7 reveals yet another alternative embodiment of the novel firstmirror adjustment means shown generally at 100. Adjustment means 100 ismounted on support stamping 34'by means of a ball joint 102 which isreceived at one end of a double ball joint receptacle or swivel spacingmember 104. A double ball joint having second and third ball joints 106and 108 joined by an interconnecting rod 110, generally in the shape ofa V, interconnects double ball joint receptacle 104 with a second doubleball joint receptacle 112. Ball joint 106 is received in the second endof receptacle 104 and ball joint 108 is received in one end of thedouble ball joint receptacle 112. The remaining end of receptacle 112receives a ball joint. 114 mounted on the back of first mirror 26. Thus,as is apparent from the phantom lines in FIG. 7, the combination balljoint which comprises the novel adjustment means 100 may be extended orretracted along an axis parallel to the central sightline 28a toaccommodate shorter or taller vehicle drivers merely by movement of oneor more of the swivel ball joints.

In summary then, utilization of any of the mirror supporting andadjusting means 30, 50, or 70 will allow the accommodation of 95 percentof the various sized individuals who will utilize the periscope system.Additionally, the use of supporting and adjusting means 100 will allowthe accommodation of approximately 80 percent of the various sizedindividuals who will utilize the periscope system. As shown in FIG. 8,the periscope system, as made adjustable by any of the first mirrorsupporting and adjustment means 30, 50, or 70 is designed to accommodateall persons whose eye position falls within the driver eye ellipse showntherein. The ellipse represents approximately 95 percent of the eyepositions of the average drivers in the population when they are sittingin the vehicle adjacent the periscope system. This ellipse generallyincludes most drivers since conventional and commonly used seats andseat adjustment mechanisms cause eye positions to fall within this area.Further, many person s eye positions will lie along or adjacent thehorizontal plane through the center of the ellipse with the eyepositions of taller and shorter persons varying on either side of thatplane. Thus, to accommodate taller persons, as shown in FIG. 8, any ofthe first mirror-supporting and adjustment means may be adjusted to movefirst mirror 26 to the proper height, closer to mirror 22, i.e., toposition 26'. The total optical path length, i.e., the total of thethree distances from the drivers eyes to the first mirror 26, from thefirst mirror 26 to the second mirror 22, and from the second mirror 22to the third mirror 12, remains substantially the same, i.e., within thesame distance range, thus providing the same field of vision when themirror is properly adjusted to accommodate the various sized drivers.The total optical path length actually varies slightly for variousdrivers but generally will be within a certain distance range dependingon the overall system size, particular mirror sizes, etc. However, thisrange is generally small enough that the total optical path length canbe considered substantially the same for most drivers. The adjustmentmeans also allows the first mirror 26 to be within the range of betweenabout 30 37 above the horizontal plane of the drivers eyes for all sizesof drivers. As with the total optical path length range, this angularrange is dependent upon the overall system size, mirror sizes, etc., butis small enough to produce substantially the same head turn-up forsubstantially all drivers.

With any of the adjustment means except means 100, the major adjustmentwill be accomplished by loosening a single set screw and sliding thefirst mirror towards the second mirror along an axis parallel to thecentral sightline 28, as indicated by the dotted line in FIG. 8, therebykeeping the first mirror in exact alignment with the second and thirdmirrors in the periscope system. The same adjustment is accomplished inadjustment means 100 by simply moving the first mirror 26 towards thesecond mirror 22. Adjustments can be made also to the first mirror 26 byany of the four ball joints after the first mirror is moved to itsapproximate position.

Although any of the first mirror-supporting and adjustment means 30, 50,or will accommodate percent of the average population it will beapparent that the first mirror is always in a position for convenientlychecking the traffic situation to the rear of the vehicle, merely byshifting the eyes slightly upward. Therefore, although the system isextremely flexible in accommodating the majority of various sizeddrivers, it may be conveniently used in any position.

It will be understood that the unique adjustment capabilities of thepresent system result from adjustment of the first or viewing mirroralong the central sightline between the first and second mirrors whilemaintaining the second and third mirrors a constant distance from oneanother. Since the eye position varies for each different driver usingthe periscope system, movement of the first mirror alone in the mannerdescribed above thereby adjusts the optical path lengths between the eyeposition and the first mirror and the first mirror and the secondmirror, as described in connection with FIGS. 8 and 10, whilemaintaining the total distance between the eye position and the secondmirror substantially the same. Thus, the total optical path length fromthe eye position through all three mirrors remains substantially thesame for generally all drivers. Consequently, the same rearward field ofvision is maintained for generally all drivers. The system thus avoidsall movement or adjustment between the second and third mirrors whichwould increase or reduce the field of vision visible through the system.Additionally, adjustment of the first mirror positions the first mirrorat a relatively constant angle above eye level for generally alldrivers, i.e., within the range of approximately 30 37 above eye levelin the preferred embodiment.

The novel arrangement of the rearview periscope system as a whole may beslightly varied in order to rotate the rearview field of vision fromdirectly behind the vehicle to a field including an area to the leftrear of the vehicle. The varied novel arrangement shown in FIG. 9 isaccomplished by positioning the first mirror supporting and adjustmentmeans on the right side of the central sightline 28 instead of directlyastride the central sightline 28. That is, considering the centralsightline 28 to also be the width-wise center line of the periscopesystem as a whole, the first mirror supporting and adjustment means needbe merely positioned slightly to the right of that center line 28 inorder to increase the field of vision toward the left of that samecenter line. Thus, by shifting the first mirror supporting 9 andadjustment means 120 to the right of center line 28 in FIG. 9, the fieldof vision is shifted from the area between lines A-A to the area betweenlines B-B. Consequently, when the first mirror supporting and adjustmentmeans 120 is so positioned to the right of that center line 28, thesurface of the first mirror will be at a slight longitudinal angle Ywith the second mirror surface 122. Consequently, more light raysentering from the left side of the vehicle will strike the surface ofthe first mirror 26 which has been positioned to the right of the centerline 28 thereby enabling the driver to view a greater area to the leftof the vehicle.

While several forms of the invention have been shown and described,other forms will now be apparent to those skilled in the art. Therefore,it will be understood that the embodiments shown in the drawings anddescribed above are merely for illustrative purposes, and are notintended to limit the scope of the invention which is defined by theclaims which follow.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. In a three mirror periscopic system for motor vehicles comprising afirst mirror to be viewed by the driver of said vehicle; a third mirrorexposed to light rays from the rear of the vehicle; and a second mirrorlocated between said first and third mirrors, all of said mirrors havinga common central sightline whereby light rays from behind said vehicleare projected on said third mirror, reflected from said third mirror tosaid second mirror and then reflected from said second mirror to saidfirst mirror for viewing by the driver of said vehicle; the improvementcomprising supporting and adjustment means for adjusting only theposition of said first mirror along said sightline away from and towardsaid second mirror; and including means for supporting said secondmirror a constant distance from said third mirror; said system allowingadjustment to provide substantially the same field of view therethroughfor all drivers using said system.

2. The system of claim 1 in which means is also provided for adjustingthe angular position of the plane of said first mirror with respect tothe planes of said other mirrors.

3. The periscopic system for vehicles as described in claim 1 in whichthe mirrors are progressively larger from the first mirror, to thesecond mirror, to the third mirror whereby the side boundaries for thefield of vision of the driver from the drivers eyes are divergingplanes, said central sightline included within a focal plane extendingperpendicularly between said diverging planes, said first mirror beingadjustable along said focal plane and angularly with respect to theplanes of the other mirrors so as to be adjustable for locating the sideboundaries of said first mirror substantially on said planes.

4. The system of claim 3 in which means is also provided for adjustingthe angular position of the plane of said first mirror with respect tothe planes of said other mirrors.

5. A periscope system for vehicles as described in claim 1 wherein saidfirst mirror-supporting and adjustment means comprises a support memberattached to said vehicle having a receptacle formed to receive a slidingmember, said sliding member supporting said first mirror such that saidfirst mirror may be slid towards and away from said second mirror alongsaid sightline without changing the angular position of the plane ofsaid first mirror with respect to said second mirror.

6. A periscope system for vehicles as described in claim 1 wherein saidfirst mirror supporting and adjusting means comprises a support memberattached to said vehicle having a slot formed centrally therein, a slidecorresponding to the cross-sectional shape of said slot, means to securesaid slide in said slot, and means mounted on said slide adapted toreceive said first mirror.

7. A periscope system for vehicles as described in claim 6 wherein saidmeans adapted to receive said first mirror are mounted on said slide atan angle with respect to the direction of travel of said slide.

8. A periscope system for vehicles as described in claim 7 wherein saidmeans adapted to receive said first mirror includes a ball joint andswivel spacing member with a receptacle which receives a ball jointmounted on said first mirror.

9. A periscope system for vehicles as described in claim 6 wherein saidmeans to secure said slide in said slot includes a hole bored in saidslide and a set screw threadably received in said hole.

10. A periscope system for vehicles as described in claim 9 wherein saidset screw has an enlarged head which facilitates the tightening andloosening of said set screw.

11. A periscope system for vehicles as described in claim 6 wherein saidsupport member has capped ends such that said slide is prevented fromsliding out of said slot.

12. A periscope system for vehicles as described in claim 6 wherein saidslot and said slide have matching T-shaped cross sections.

l3.A periscope system for vehicles as described in claim 1 wherein saidfirst mirror supporting means conprises a ball joint mounted on saidvehicle; a swivel support member mounted on said ball joint and adjustedby means of a set screw threadably mounted in a hole bored in acylindrical extension in said member adapted to receive said ball joint,said member including a second hole bored therethrough whose axis isperpendicular to the hole bored in said cylindrical extension, and athird hole bored to intersect said second hole, said third hole havingan axis perpendicular to said second hole; a rod slidably mounted insaid second hole having means mounted thereon which receive said firstmirror; and a set screw threadably received in said third hole such thatsaid screw engages said rod when said rod is slidably received in saidsecond hole.

14. A periscope system for vehicles as described in claim 13 whereinsaid means which receive said first mirror is a ball joint mounted onsaid rod at an angle with respect to the sliding direction of travel ofsaid rod.

15. A periscope system for vehicles as described in claim 14 wherein aslot is cut lengthwise along at least a section of said rod such thatsaid set screw engages said rod within said slot.

16. A periscope system for vehicles as described in claim 15 whereinsaid set screw has a handle formed at a right angle to the axis of thethreads cut in said screw.

17. A periscope system for vehicles as described in claim 1 wherein saidfirst mirror supporting means comprises a base attached to said vehicle,said base having a first ball joint mounted thereon; a swivel spacingmember mounted on said first ball joint having receptacles for two balljoints, a double ball joint having second and third ball joints joinedby an interconnecting rod; and a second swivel spacing member havingreceptacles for two ball joints mounted on said third ball joint suchthat a first mirror having a ball joint mounted thereon may be receivedin the second of said two receptacles.

18. A periscope system for vehicles as described in claim 17 whereinsaid interconnecting rod is formed in the shape of a V.

19. In a three mirror periscopic system for motor vehicles comprising afirst mirror to be viewed by the driver of said vehicle; a third mirrorexposed to light rays from the rear of the vehicle; and a second mirrorlocated between said first and third mirrors, said second and thirdmirrors having a common central sightline whereby light rays from behindsaid vehicle are projected on said third mirror, reflected from saidthird mirror to said second mirror and then reflected from said secondmirror to said first mirror for viewing by the driver of said vehicle;the improvement comprising supporting and adjustment means for adjustingthe position of said first mirror along said sightline away from andtoward said second mirror; said first mirrorsupporting and adjustmentmeans, including said first mirror,displaced to the side of said centralsightline of said second and third mirrors such that the angle definingthe field of vision is rotated, thereby including a greater field ofvision on the side of said central sightline opposite the direction ofdisplacement of said improved first mirror supporting and adjustmentmeans.

1. In a three mirror periscopic system for motor vehicles comprising afirst mirror to be viewed by the driver of said vehicle; a third mirrorexposed to light rays from the rear of the vehicle; and a second mirrorlocated between said first and third mirrors, all of said mirrors havinga common central sightline whereby light rays from behind said vehicleare projected on said third mirror, reflected from said third mirror tosaid second mirror and then reflected from said second mirror to saidfirst mirror for viewing by the driver of said vehicle; the improvementcomprising supporting and adjustment means for adjusting only theposition of said first mirror along said sightline away from and towardsaid second mirror; and including means for supporting said secondmirror a constant distance from said third mirror; said system allowingadjustment to provide substantially the same field of view therethroughfor all drivers using said system.
 2. The system of claim 1 in whichmeans is also provided for adjusting the angular position of the planeof said first mirror with respect to the planes of said other mirrors.3. The periscopic system for vehicles as described in claim 1 in whichthe mirrors are progressively larger from the first mirror, to thesecond mirror, to the third mirror whereby the side boundaries for thefield of vision of the driver from the driver''s eyes are divergingplanes, said central sightline included within a focal plane extendingperpendicularly betwEen said diverging planes, said first mirror beingadjustable along said focal plane and angularly with respect to theplanes of the other mirrors so as to be adjustable for locating the sideboundaries of said first mirror substantially on said planes.
 4. Thesystem of claim 3 in which means is also provided for adjusting theangular position of the plane of said first mirror with respect to theplanes of said other mirrors.
 5. A periscope system for vehicles asdescribed in claim 1 wherein said first mirror-supporting and adjustmentmeans comprises a support member attached to said vehicle having areceptacle formed to receive a sliding member, said sliding membersupporting said first mirror such that said first mirror may be slidtowards and away from said second mirror along said sightline withoutchanging the angular position of the plane of said first mirror withrespect to said second mirror.
 6. A periscope system for vehicles asdescribed in claim 1 wherein said first mirror supporting and adjustingmeans comprises a support member attached to said vehicle having a slotformed centrally therein, a slide corresponding to the cross-sectionalshape of said slot, means to secure said slide in said slot, and meansmounted on said slide adapted to receive said first mirror.
 7. Aperiscope system for vehicles as described in claim 6 wherein said meansadapted to receive said first mirror are mounted on said slide at anangle with respect to the direction of travel of said slide.
 8. Aperiscope system for vehicles as described in claim 7 wherein said meansadapted to receive said first mirror includes a ball joint and swivelspacing member with a receptacle which receives a ball joint mounted onsaid first mirror.
 9. A periscope system for vehicles as described inclaim 6 wherein said means to secure said slide in said slot includes ahole bored in said slide and a set screw threadably received in saidhole.
 10. A periscope system for vehicles as described in claim 9wherein said set screw has an enlarged head which facilitates thetightening and loosening of said set screw.
 11. A periscope system forvehicles as described in claim 6 wherein said support member has cappedends such that said slide is prevented from sliding out of said slot.12. A periscope system for vehicles as described in claim 6 wherein saidslot and said slide have matching T-shaped cross sections.
 13. Aperiscope system for vehicles as described in claim 1 wherein said firstmirror supporting means conprises a ball joint mounted on said vehicle;a swivel support member mounted on said ball joint and adjusted by meansof a set screw threadably mounted in a hole bored in a cylindricalextension in said member adapted to receive said ball joint, said memberincluding a second hole bored therethrough whose axis is perpendicularto the hole bored in said cylindrical extension, and a third hole boredto intersect said second hole, said third hole having an axisperpendicular to said second hole; a rod slidably mounted in said secondhole having means mounted thereon which receive said first mirror; and aset screw threadably received in said third hole such that said screwengages said rod when said rod is slidably received in said second hole.14. A periscope system for vehicles as described in claim 13 whereinsaid means which receive said first mirror is a ball joint mounted onsaid rod at an angle with respect to the sliding direction of travel ofsaid rod.
 15. A periscope system for vehicles as described in claim 14wherein a slot is cut lengthwise along at least a section of said rodsuch that said set screw engages said rod within said slot.
 16. Aperiscope system for vehicles as described in claim 15 wherein said setscrew has a handle formed at a right angle to the axis of the threadscut in said screw.
 17. A periscope system for vehicles as described inclaim 1 wherein said first mirror supporting means comprises a baseattached to said vehicle, said basE having a first ball joint mountedthereon; a swivel spacing member mounted on said first ball joint havingreceptacles for two ball joints, a double ball joint having second andthird ball joints joined by an interconnecting rod; and a second swivelspacing member having receptacles for two ball joints mounted on saidthird ball joint such that a first mirror having a ball joint mountedthereon may be received in the second of said two receptacles.
 18. Aperiscope system for vehicles as described in claim 17 wherein saidinterconnecting rod is formed in the shape of a V.
 19. In a three mirrorperiscopic system for motor vehicles comprising a first mirror to beviewed by the driver of said vehicle; a third mirror exposed to lightrays from the rear of the vehicle; and a second mirror located betweensaid first and third mirrors, said second and third mirrors having acommon central sightline whereby light rays from behind said vehicle areprojected on said third mirror, reflected from said third mirror to saidsecond mirror and then reflected from said second mirror to said firstmirror for viewing by the driver of said vehicle; the improvementcomprising supporting and adjustment means for adjusting the position ofsaid first mirror along said sightline away from and toward said secondmirror; said first mirror-supporting and adjustment means, includingsaid first mirror, displaced to the side of said central sightline ofsaid second and third mirrors such that the angle defining the field ofvision is rotated, thereby including a greater field of vision on theside of said central sightline opposite the direction of displacement ofsaid improved first mirror supporting and adjustment means.